1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___ALGORITHM_COPY_N_H
10#define _LIBCPP___ALGORITHM_COPY_N_H
11
12#include <__algorithm/copy.h>
13#include <__algorithm/iterator_operations.h>
14#include <__config>
15#include <__iterator/iterator_traits.h>
16#include <__type_traits/enable_if.h>
17#include <__utility/convert_to_integral.h>
18#include <__utility/move.h>
19#include <__utility/pair.h>
20
21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22# pragma GCC system_header
23#endif
24
25_LIBCPP_PUSH_MACROS
26#include <__undef_macros>
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30template <class _AlgPolicy,
31 class _InIter,
32 class _OutIter,
33 __enable_if_t<__has_random_access_iterator_category<_InIter>::value, int> = 0>
34_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>
35__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {
36 return std::__copy(__first, __first + __n, std::move(__result));
37}
38
39template <class _AlgPolicy,
40 class _InIter,
41 class _OutIter,
42 __enable_if_t<!__has_random_access_iterator_category<_InIter>::value, int> = 0>
43_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InIter, _OutIter>
44__copy_n(_InIter __first, typename _IterOps<_AlgPolicy>::template __difference_type<_InIter> __n, _OutIter __result) {
45 while (__n != 0) {
46 *__result = *__first;
47 ++__first;
48 ++__result;
49 --__n;
50 }
51 return std::make_pair(std::move(__first), std::move(__result));
52}
53
54// The InputIterator case is handled specially here because it's been written in a way to avoid incrementing __first
55// if not absolutely required. This was done to allow its use with istream_iterator and we want to avoid breaking
56// people, at least currently.
57// See https://github.com/llvm/llvm-project/commit/99847d2bf132854fffa019bab19818768102ccad
58template <class _InputIterator,
59 class _Size,
60 class _OutputIterator,
61 __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
62_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
63copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {
64 using _IntegralSize = decltype(std::__convert_to_integral(__n));
65 _IntegralSize __converted = __n;
66 if (__converted > 0) {
67 *__result = *__first;
68 ++__result;
69 for (--__converted; __converted > 0; --__converted) {
70 ++__first;
71 *__result = *__first;
72 ++__result;
73 }
74 }
75 return __result;
76}
77
78template <class _InputIterator,
79 class _Size,
80 class _OutputIterator,
81 __enable_if_t<!__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
82_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
83copy_n(_InputIterator __first, _Size __n, _OutputIterator __result) {
84 using _IntegralSize = decltype(std::__convert_to_integral(__n));
85 _IntegralSize __converted = __n;
86 return std::__copy_n<_ClassicAlgPolicy>(__first, __iterator_difference_type<_InputIterator>(__converted), __result)
87 .second;
88}
89
90_LIBCPP_END_NAMESPACE_STD
91
92_LIBCPP_POP_MACROS
93
94#endif // _LIBCPP___ALGORITHM_COPY_N_H
95